Sequencer 3D Trajectories run very slow on deep hierarchies

Using a Level Sequence with deep hierarchies causes the FPS to drop to low numbers when they are all selected within the Sequence. This is a regression from 4.19.2 (CL-4033788).

This issue was reported and tested in 4.20.2 (CL-4302132. This was reproduced in Main 4.21 (CL-4313833).

1. Download and open the attached project
2. Toggle Show FPS in the Viewport
3. Select all the Cubes in the World Outliner and notice the FPS change
4. Open the Level Sequence in the Content Browser
5. Select all the Cubes and Transforms in the Level Sequence and notice the FPS change

Results: FPS drops between 3 and 6

Expected: FPS doesn't take a heavy drop